drm/i915/dp: Generalize intel_dp_link_params function to accept arguments to be validated

This function now takes the link rate and lane ocunt to be validated
as an argument so that this can be used for validating even the
compliance test link parameters.

Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@linux.intel.com>
Tested-by: Nathan Ciobanu <nathan.d.ciobanu@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1496954463-18038-1-git-send-email-manasi.d.navare@intel.com